Effect of systemic tetracycline on progression of Pseudomonas aeruginosa keratitis in the rabbit.

Tetracycline has anticollagenase activity in human and animal tissues. Recent evidence shows collagenase to be instrumental in the progression of infectious and noninfectious corneal ulceration. We investigated the effect of systemic tetracycline on the incidence of corneal perforation in Pseudomonas aeruginosa ulcerative keratitis in rabbits. Twenty rabbits were assigned randomly to two groups in a masked fashion. All corneas were inoculated with 10(6) P. aeruginosa organisms. Ten rabbits (20 eyes) received intramuscular tetracycline 50mg/kg/day in a saline vehicle (treatment group), and ten rabbits (20 eyes) received saline alone (control group) for ten days. The incidence of corneal perforation in the treatment group (45%) was significantly lower than that in the control group (80%, P less than .02). This appeared to be independent of any antimicrobial effect from tetracycline. Administration of tetracycline may be a useful adjunct in the treatment of P. aeruginosa corneal ulcers.